The Tennessee Valley Authority lost $173 million in the final three months of calendar 2011 as milder winter temperatures cut electricity sales by $260 million compared with the same time a year ago.

In a filing with the U.S. Securities and Exchange Commission, TVA said today it is revising its revenues estimates for this year downward by 2 percent and looking for ways to cut its spending in fiscal 2012.

TVA reported a net loss of $173 million on revenues of $2.4 billion in the three months ending Dec. 31. In the same quarter a year ago, TVA lost $48 million on revenues of nearly $2.6 billion.

"Milder weather as compared to the abnormally cold weather for the same period of the prior year was responsible for a 6 percent decrease in sales of electricity to TVA's municipalities and cooperatives," TVA said in its regulatory filing released this morning. "Customers of municipalities and cooperatives are primarily residential customers whose usage of electricity is typically more temperature sensitive than that of industrial customers."

TVA had projected annual sales this year to total $12.1 billion, but the milder winter and economy are likely to cut that total by about $240 million, TVA said in a 54-page filing with the SEC today.

" The lower than expected sales and resulting lower revenue, exclusive of fuel and purchased power cost recovery, is causing TVA to revisit expenditures for 2012 which may include project scope and schedule revisions related to operations, revisions of certain programs and initiatives and other productivity enhancement initiatives," TVA said in its report.